Fluorescent light control



Sept. 17, 1946. c. F. RUDOLPH 2,407,685

I FLUORESCENT LI GHT CONTROL Filed Aug. 3, 1943 2 Sheets-She'et 1 INVENTOR. Corrie E Rudolph v AttO/Jiff Sept. 17, 1946. c RUDQLPH 2,407,685

FLUORESCENT LIGHT CONTROL Filed Aug. 3, 1945 I 2 Sheets-Sheet 2 INVENTORL: Corrie E Rudolph Attorney Patented Sept. 17, 1946 UNITED STATES PATENT OFFICE FLUORESCENT LIGHT CONTROL Corrie F. Rudolph, Washington, D. C.

Application August 3, 1943, Serial No. 497,275

(Granted under the act of March 3, 1883, as

8 Claims.

amended April 30, 1928; 370 O. G. 757) V This invention relates to a voltage control for gaseous discharge lamps which are designed for production of fluorescent radiation for general lighting.

The principal object of my invention is to provide means in a fluorescent tube to eliminate sources of frequent failures to start, burned out ballasts, blackened tubes and radio interference due to failure to start.

Another object of my invention is to provide an arrangement of fluorescent illuminating tube system in which potentials may be established at opposite terminals internally of the tube without regard to the completeness of the conventional cathode or filament circuit normally provided in such fluorescent tubes.

Still another object of my invention is to provide a circuit arrangement for operating fluorescent tubes in a manner in which conventional fluorescent tubes having internal cathodes which have been burned out and which normally render such tubes worthless, may be so arranged in an electrical power supply circuit as to enable the fluorescent tube to be usefully employed throughout an additional period of illuminating life.

Other and further objects of my invention reside in the structural means by which conventional fluorescent tubes may be converted for useful operation over an additional period of illuminating life as set forth more fully in the specification hereinafter following by reference to the accompanying drawings in which:

Fig. 1 is a circuit diagram showing the improved circuit arrangement for fluorescent tubes arranged in accordance with my invention; Fig. 2 is a schematic view showing a fluorescent tube mounted in a manner employing the principles of my invention; Fig. 3 is a view through one of the supporting tube socket members or cases showing the conversion means I employ for utilizing fluorescent tubes heretofore burned out and discarded; and Fig. 4 is a transverse sectional view substantially on line 4-4 of Fig. 2 showing the portions of the tube cathode or filament which are employed in the system of my invention wholly as a discharge anode.

In order that the above objects may be realized it is considered necessary to eliminate the usual starter button, and its associated filaments within the fluorescent lamp, power factor correction condensers and all auxiliary breaks in the circuit after having energized the circuit. With the above devices eliminated, the voltage regulation requirements for a standard commercial 40 watt fluorescent lamp with 115 volt A. C. line will range from 125 to 325 Volts, depending on age, gas content and temperature of tube for initial starting and approximately 100 to 108 volts for running condition. This change in voltage from 325 volts to 100 volts should automatically follow the changing resistance characteristics of the gas within the fluorescent lamp during the transition from a cold gas to a completely ionized condition. The required voltage regulation was obtained by utilizing the temperature resistance characteristics of the tungsten filament of an incandescent lamp incorporated in the control circuit of the fluorescent lamp, and in conjunction with an inductive device the windings of which are so arranged to produce full line voltage on the incandescent lamp, thus obtaining its full value as a light source and thereby reducing the overall strob-oscopic eifect, This type of control will permit wide fluctuations in line voltage, selective control of light intensity by means of switching connections or change in wattage of ballast lamps (incandescent lamp). In the circuit herein described the wattage and light intensity of the fluorescent lamp varies directly with the wattage of the ballast lamps. The percentage of watts lost in the inductive device described herein is approximately less than the present commercial chokes used with starter button type of controls.

The windings of the inductive device are so arranged that the inductance of the primary and secondary practically cancel each other underrunning condition resulting in a near unity power factor, neglecting the intermittent phase displacement due to distortion of the wave form by the tube itself.

Since the starting current is less than running current, failure of the lamp to start or neglect to replace a defective lamp cannot injure the control. Maintenance costs are therefore substantially limited to the item of lamp replacements.

The control described herein is designed to operate present commercial general lighting fluorescent tubes, having their filaments short circuited in the tube socket, thus functioning as a cold electrode. Only one terminal is needed and a simplified equivalent electrode within the fluorescent lamp may be used and accordingly burned out filaments will not make the lamp in operative. The inductive device described here in consists of a closed iron core transformer, of the low loss, non-saturated core type. The primary and secondary winding are wound continu ously with tap as shown and when connected as shown in the circuit diagram of Fig. 1 will function as a step-up transformer in combination with a gaseous discharge tube having a negative resistance temperature coeflicient, entirely controlled by the resistance through the gaseous path within the fluorescent lamp. Success in starting and operating fluorescent lamps which have failed in the :ordinary commercial control is attributed primarily to the continuous 60 cycle starting current. The intermittent starting cycle of the ordinary commercial control permits the gas within the fluorescent lamp to cool between starting impulses, thus necessitating the premature discard of the lamp.

Referring to the drawings in detail, the fluorescent lamp of conventional construction is indicated by reference character I associated in electrical circuit with an iron core transformer or inductive device 2. The iron core transformer or inductive device 2 includes an iron core which carries an auto-transformer circuit including a primary winding 3 and a secondary winding 4. The primary winding 3 is connected to the conventional power supply 'line 5. The power supply line is indicated as including an incandescent lamp bank, heater elements or motor represented at 6. A switch is provided, including a switch arm 9, and switch contacts I and 8. Switch contact I is arranged for low intensity light operation. Switch contact 8 is arranged for high intensity light operation.

The conventional fluorescent lamp which is represented as having terminal posts I! and I8 projecting from each end thereof and normally connected in circuit with the tube filaments or cathodes 2I arranged internally of each end of the tube. An arc shield I9 is arranged in the end of the tube on one side of the filament 2| "and a complementary arc shield 20 is arranged in the end of the tube on the opposite side of the filament 2| as represented in Fig. 4.

The terminal posts I! and I8, projecting from the opposite ends of the tube, are engageable in socket members or cases I arranged to insulatingly mount the fluorescent tube with respect to 'abase plate or mounting fixture II. Each of the socket members or cases It! form housings for contact springs I2 and I3 which are shaped for engagement with the terminal posts [I and I8 of the fluorescent tube. The contact springs I2 and I3 are mounted in the socket members or cases I0 terminating in terminal posts It and I as "shown.

Ordinarily electric circuit connections are taken from the separate and insulatingly supported terminal posts l4 and IE to the starting and running circuit of the fluorescent lamp. In the system of m invention, however, I entirely depart from the conventional practice of establishing circuit connections to each of the terminal posts I4 and I5 for forming a series circuit through the cathodes or filaments I2 at each end of the fluorescentv tube. In lieu of such separate connection, I provide a short circuiting bus connection between terminal posts i4 and I5. I have shown this short circuiting connection provided by means of lengths of wire 23 and 24 which are fastened beneath the heads of the screws forming the terminal posts I4 and I5 and brought up through the aperture 25 in the base plate or support II and twisted together as represented at I6, forming a short circuit across the ends of the filaments or cathodes. The shunted ends of the filament through the short circuit connection I6 are then electrically con- 4 nected in the power supply circuit as represented in Fig. 1.

I may provide a condenser 22 shown in shunt connection with the terminals leading to the fluorescent tube. This small condenser, arranged as shown, eliminates the fluorescent tube as a source of radio interference. "Some fluorescent tubes have a tendency to emit radio frequency energy with a 60 cycle modulation superimposed thereon. This is a continuous phenomenon unrelated to radio interference due to starting conditions to which I have heretofore referred.

.By virtue of the direct connection to the oathodes or filaments in the opposite ends of the fluorescent tube, I am able to utilize fluorescent lamps which have already served their useful life but in which the cathodes or filaments have burned open. Inasmuch as a series path through the cathode or filament is unnecessary to the operation of the tube system of my invention as an illuminating means, I am able to economically extend the life of fluorescent tubes almost indefinitely. Moreover burned out tubes heretofore used in conventional circuits may now be used in the system of my invention over an additional period of useful life.

While I have described my invention in one of :its preferred embodiments, I desire that it be understood that modifications may be made and I intend no limitations upon my invention other than may be imposed by the scope of the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

'1. A voltage control for a gaseous discharge tube having a negative resistance temperature c'oeflicient, comprising in combination with a gaseous discharge tube having a negative resist- "ance temperature coefficient, an inductive device and. an incandescent lamp having a positive resistance temperature coefiicient for the purpose of providing starting and running voltages for said tube, said inductive device being provided with primary and secondary windings arranged so that the primary winding will react upon the secondary winding during starting to produce necessary starting voltages and the secondary winding to react upon the primary winding during running 'to counteract the inductance of the primary winding plus D. C. resistance of the primary winding and thereby produce full line voltage on the incandescent lamp for the purpose of obtaining full illumination from the incandescent lamp and consequent reduction in overall stroboscopic effect. I

2. A gaseous discharge tube system comprising a gaseous discharge tube having a pair of pin terminals projecting from each end thereof, cathodes disposed interiorly of the ends of said tube and connected with said pin terminals, socket devices for mechanically engaging said pin terminals, a pair of contact members in each of said socket devices for establishing electrical connection with said pin terminals, a bus permanent- 1y connected between each of saidpai'r of contact members for continuously short circuiting said contact members independently of whether the pin terminals of said tube are engaged in said socket device or not, an alternating current power supply source, and a device having a positive temperature coefficient of resistance, said device being an inductive device connected in circuit with said power supply source and connected through said bus with the short circuited terminals of said gaseous discharge tube.

3. A gaseous discharge tube system comprising a gaseous discharge tube having a pair of pin terminals projecting from each end thereof, cathodes disposed interiorly of the ends of said tube and connected with said pin terminals, socket devices for mechanically engaging said pin terminals, 2. pair of contact members in each of said socket devices for establishing electrical connection with said pin terminals, a shunt connection permanently interconnecting each of said pair of contact members, an alternating current power supply source, a device having a positive temperature coetficient of resistance, an inductive device including a pair of series connected windings, both of said devices being connected in circuit with said power supply source and connected permanently with said shunt connections- 4. A gaseous discharge tube system comprising a gaseous discharge tube having a pair of pin terminals projecting from each end thereof, cathodes disposed interiorly of the ends of said tube and connected with said pin terminals, socket devices for mechanically engaging said pin terminals, a pair of contact members in each of said socket devices for establishing electrical connection with said pin terminals, a shunt connection connected between each of said pair of contact members, an alternating current power supply source, an inductive device including a pair of windings, a load, a connection between said power supply source through said load to one end of one of the windings of said inductive device, a connection from the other side of said power supply source to the other end of said last mentioned winding of said inductive device, a circuit path from said last mentioned end of said last mentioned winding through said other winding to one of said shunt connections, a switch device movable to either of two positions, a connection between said switch device and the other of said shunt connections, and means for establishing connection through said switch device with the first mentioned side of said power supply source on either side of said load with respect to the end of the winding with which said load is connected.

5. A composite incandescent and fluorescent illuminating structure comprising in combination with an alternating current power supply source an iron core reactor including a, winding tapped intermediate the ends thereof, an incandescent lamp load, a series path from said power source through the tapped connection to said reactor and through one end of said reactor to said incandescent lamp load returning to said power source, the fluorescent lamp having an electrode in each end thereof, a connection between one of said electrodes and the opposite end of said reactor, a connection between the other of-said electrodes to a selector switch and contacts for said selector switch on opposite sides of said incandescent lamp load for selectively establishing connection from the last mentioned electrode of said fluorescent lamp with one side of said alternating current power source or with the said side of said power source through said alternating current incandescent lamp load.

6. A fluorescent light control comprising a fluorescent light circuit, an incandescent lamp designed for operation at full line voltage from an alternating current power supply source, an impedance in series with said incandescent lamp and with said alternating current power supply source, said impedance being automatically neutralized by the current in the fluorescent light circuit to cause the incandescent lamp to burn at rated voltage, and to provide starting and running voltage and current for the fluorescent light.

7. A fluorescent light control comprising a I fluorescent light circuit, an incandescent lamp designed for operation at full line voltage from an alternating current power supply source, an impedance in series with said incandescent lamp, said impedance being automaticallyneutralized by the inductive effect of the current in the fluorescent light circuit to cause the incandescent lamp to burn at rated voltage and to provide starting and running voltage and current for the fluorescent light at substantially overall unity power factor.

8. A voltage control for a gaseous discharge tube having a negative resistance temperature coeflicient, comprising in combination with a gaseous discharge tube having a negative resistance temperature coeflicient, an inductive device and an element having a positive resistance temperature coeflicient for providing starting and running voltages for said tube, said inductive device being provided with primary and secondary windings having substantially the same inductive effect and disposed in inductance opposition to effect an overall power factor approximating unity during normal operation.

CORRIE F. RUDOLPH. 

